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MySQL load NULL values from CSV data
... up containing an empty string:
LOAD DATA INFILE '/tmp/testdata.txt'
INTO TABLE moo
FIELDS TERMINATED BY ","
LINES TERMINATED BY "\n"
(one, two, three, @vfour, five)
SET four = NULLIF(@vfour,'')
;
If they're all possibly empty, then you'd read them all into variables and have multiple SET stateme...
postgresql: INSERT INTO … (SELECT * …)
...connect remote database and fetch result. For example:
psql dbtest
CREATE TABLE tblB (id serial, time integer);
INSERT INTO tblB (time) VALUES (5000), (2000);
psql postgres
CREATE TABLE tblA (id serial, time integer);
INSERT INTO tblA
SELECT id, time
FROM dblink('dbname=dbtest', 'SELECT ...
What are the underlying data structures used for Redis?
...e implemented with linked lists.
Sets and Hashes are implemented with hash tables.
Sorted sets are implemented with skip lists (a peculiar type of balanced trees).
But when lists, sets, and sorted sets are small in number of items and size of the largest values, a different, much more compact enco...
How many characters can UTF-8 encode?
...
According to this table* UTF-8 should support:
231 = 2,147,483,648 characters
However, RFC 3629 restricted the possible values, so now we're capped at 4 bytes, which gives us
221 = 2,097,152 characters
Note that a good chunk of those chara...
What are POD types in C++?
...l be no "magic" going on in the structure: for example hidden pointers to vtables, offsets that get applied to the address when it is cast to other types (at least if the target's POD too), constructors, or destructors. Roughly speaking, a type is a POD when the only things in it are built-in types ...
Can we use join for two different database tables?
Can we use the join operation for two tables from different databases? If yes, how do I do it?
2 Answers
...
Regular expression for a string that does not start with a sequence
I'm processing a bunch of tables using this program , but I need to ignore ones that start with the label "tbd_". So far I have something like [^tbd_] but that simply not match those characters.
...
Determine if string is in list in JavaScript
... (i--) {/*use a[i]*/} is the fastest loop method (if reverse order is acceptable).
– ErikE
Mar 12 '10 at 2:31
...
What is the argument for printf that formats a long?
...y really really knew what they were doing editing a piece of x-platform portable code. Even then, they probably would have used a macro instead to capture the semantic meaning of the type (eg uint64_t).
char c; // 8 bits
short s; // 16 bits
int i; // 32 bits (on modern platforms)...
printf with std::string?
...has a place that can't easily be filled by C++ syntactic features, just as table structures in html have a place that can't easily be filled by divs. As Dykstra wrote later about the goto, he didn't intend to start a religion and was really only arguing against using it as a kludge to make up for p...